Author: kwright
Date: Wed Nov 6 19:38:06 2013
New Revision: 1539438
URL: http://svn.apache.org/r1539438
Log:
Construct a zookeeper client object
Modified:
manifoldcf/branches/CONNECTORS-13/framework/core/src/main/java/org/apache/manifoldcf/core/lockmanager/ZookeeperLockManager.java
Modified:
manifoldcf/branches/CONNECTORS-13/framework/core/src/main/java/org/apache/manifoldcf/core/lockmanager/ZookeeperLockManager.java
URL:
http://svn.apache.org/viewvc/manifoldcf/branches/CONNECTORS-13/framework/core/src/main/java/org/apache/manifoldcf/core/lockmanager/ZookeeperLockManager.java?rev=1539438&r1=1539437&r2=1539438&view=diff
==============================================================================
---
manifoldcf/branches/CONNECTORS-13/framework/core/src/main/java/org/apache/manifoldcf/core/lockmanager/ZookeeperLockManager.java
(original)
+++
manifoldcf/branches/CONNECTORS-13/framework/core/src/main/java/org/apache/manifoldcf/core/lockmanager/ZookeeperLockManager.java
Wed Nov 6 19:38:06 2013
@@ -36,11 +36,44 @@ public class ZookeeperLockManager extend
{
public static final String _rcsid = "@(#)$Id: LockManager.java 988245
2010-08-23 18:39:35Z kwright $";
+ protected final static String zookeeperConnectStringParameter =
"org.apache.manifoldcf.zookeeper.connectstring";
+ protected final static String zookeeperSessionTimeoutParameter =
"org.apache.manifoldcf.zookeeper.sessiontimeout";
+
+ // Zookeeper construction values
+ protected final String connectString;
+ protected final int sessionTimeout;
+
+ // One zookeeper client per thread
+ protected ZooKeeper zookeeper = null;
+ protected ZookeeperWatcher zookeeperWatcher = null;
+
/** Constructor */
public ZookeeperLockManager()
throws ManifoldCFException
{
- // MHL
+ connectString =
ManifoldCF.getStringProperty(zookeeperConnectStringParameter,null);
+ if (connectString != null)
+ throw new ManifoldCFException("Zookeeper lock manager requires a valid
"+zookeeperConnectStringParameter+" property");
+ sessionTimeout =
ManifoldCF.getIntProperty(zookeeperSessionTimeoutParameter,300000);
+ }
+
+ public ZooKeeper getSession()
+ throws ManifoldCFException
+ {
+ if (zookeeper == null)
+ {
+ try
+ {
+ ZookeeperWatcher zookeeperWatcher = new ZookeeperWatcher();
+ zookeeper = new ZooKeeper(connectString, sessionTimeout,
zookeeperWatcher);
+ this.zookeeperWatcher = zookeeperWatcher;
+ }
+ catch (IOException e)
+ {
+ throw new ManifoldCFException("Zookeeper initialization error:
"+e.getMessage(),e);
+ }
+ }
+ return zookeeper;
}
/** Get the current shared configuration. This configuration is available
in common among all nodes,
@@ -124,6 +157,36 @@ public class ZookeeperLockManager extend
public void enterWriteLock(String lockKey)
throws ManifoldCFException
{
+ // From Zookeeper recipes
+
+ /*
+ 1. Call create( ) to create a node with pathname "guid-/write-". This is
the lock node
+ spoken of later in the protocol. Make sure to set both sequence and
ephemeral flags.
+ If a recoverable error occurs calling create() the client should call
getChildren() and
+ check for a node containing the guid used in the path name. This
handles the case
+ (noted above) of the create() succeeding on the server but the server
crashing before
+ returning the name of the new node.
+ */
+
+ /*
+ 2. Call getChildren( ) on the lock node without setting the watch flag -
this is important,
+ as it avoids the herd effect.
+ */
+
+ /*
+ 3. If there are no children with a lower sequence number than the node
created in step
+ 1, the client has the lock and the client exits the protocol.
+ */
+
+ /*
+ 4. Call exists( ), with watch flag set, on the node with the pathname that
has the next
+ lowest sequence number.
+ */
+
+ /* 5. If exists( ) returns false, goto step 2. Otherwise, wait for a
notification for the
+ pathname from the previous step before going to step 2.
+ */
+
// MHL
}
@@ -149,6 +212,12 @@ public class ZookeeperLockManager extend
public void leaveWriteLock(String lockKey)
throws ManifoldCFException
{
+ // From Zookeeper recipes
+
+ /*
+ Delete the node we created in step 1 above.
+ */
+
// MHL
}
@@ -204,6 +273,41 @@ public class ZookeeperLockManager extend
public void enterReadLock(String lockKey)
throws ManifoldCFException
{
+
+ // From Zookeeper recipes
+
+ /*
+ 1. Call create( ) to create a node with pathname "guid-/read-". This is
the lock node use later in the
+ protocol. Make sure to set both the sequence and ephemeral flags.
+ If a recoverable error occurs calling create() the client should call
getChildren() and
+ check for a node containing the guid used in the path name. This
handles the case
+ (noted above) of the create() succeeding on the server but the server
crashing before
+ returning the name of the new node.
+ */
+
+ /*
+ 2. Call getChildren( ) on the lock node without setting the watch flag -
this is important, as it
+ avoids the herd effect.
+ */
+
+ /*
+ 3. If there are no children with a pathname starting with "write-" and
having a lower
+ sequence number than the node created in step 1, the client has the
lock and can exit the protocol.
+ */
+
+ /*
+ 4. Otherwise, call exists( ), with watch flag, set on the node in lock
directory with pathname
+ staring with "write-" having the next lowest sequence number.
+ */
+
+ /*
+ 5. If exists( ) returns false, goto step 2.
+ */
+
+ /*
+ 6. Otherwise, wait for a notification for the pathname from the previous
step before going to step 2
+ */
+
// MHL
}
@@ -228,6 +332,12 @@ public class ZookeeperLockManager extend
public void leaveReadLock(String lockKey)
throws ManifoldCFException
{
+ // From Zookeeper recipes
+
+ /*
+ Delete the node we created in step 1 above.
+ */
+
// MHL
}
@@ -284,4 +394,18 @@ public class ZookeeperLockManager extend
// MHL
}
+ /** Watcher class for zookeeper, so we get notified about zookeeper events.
*/
+ protected static class ZookeeperWatcher implements Watcher
+ {
+ public ZookeeperWatcher()
+ {
+ // MHL
+ }
+
+ public void process(WatchedEvent event)
+ {
+ // MHL
+ }
+
+ }
}
